CCSDS_pkt_chksum.c File Reference

Function definitions for CCSDS packet checksum library. More...

#include <CCSDS/CCSDS_pkt.h>
#include <CCSDS_pkt_private.h>
#include <PBI/PTR.h>

Functions
Packet Checksum Functions
unsigned int	CCSDS_pktChksumSizeof (void)
	Get the size of a CCSDS telecommand packet checksum.
unsigned short	CCSDS_pktChksumCalc (const void *pkt, int size)
	Calculate a packet checksum value.
unsigned int	CCSDS_pktChksumInsert (void *pkt, int size)
	Calculate and insert a packet checksum.
unsigned int	CCSDS_pktChksumVerify (const void *pkt, int size)
	Verify a packet checksum value.

---

Detailed Description

Function definitions for CCSDS packet checksum library.

Author:

D.L. Wood

---

Function Documentation

unsigned short CCSDS_pktChksumCalc	(	const void *	pkt,
		int	size
	)

Calculate a packet checksum value.

Calculates the value of a packet checksum over a range of packet data. The algorithm is:

1. Start with an initial checksum value of '0'.
2. Add the next byte from the data to the running checksum value.
3. Advance to the next word and go to step 2.

Parameters:

	pkt	A pointer to the beginning of the range to checksum.
	size	The number of bytes to checksum.

Returns:

The checksum value.

Referenced by CCSDS_pktChksumInsert(), and CCSDS_pktChksumVerify().

unsigned int CCSDS_pktChksumInsert	(	void *	pkt,
		int	size
	)

Calculate and insert a packet checksum.

Calculates the value of a packet checksum over a range of packet data. The checksum value is inserted at the proper location at the end of the packet application data.

Parameters:

	pkt	A pointer to the beginning of the range to checksum (packet header).
	size	The total number of bytes in the packet including packet header and checksum slot.

Returns:

A CSDS MSG value.

References CCSDS_PKT_MSG, CCSDS_pktChksumCalc(), and NULL.

unsigned int CCSDS_pktChksumSizeof

(

void

)

Get the size of a CCSDS telecommand packet checksum.

Returns the size in bytes of a CCSDS telecommand packet checksum word.

Returns:

The checksum size.

References CCSDS_PKT_CHKSUM_SIZE.

unsigned int CCSDS_pktChksumVerify	(	const void *	pkt,
		int	size
	)

Verify a packet checksum value.

Calculates the value of a packet checksum over a range of packet data. The checksum value is compared to the value stored at the end of the packet application data.

Parameters:

	pkt	A pointer to the beginning of the range to checksum (packet header).
	size	The total number of bytes in the packet including packet header and checksum slot.

Returns:

A CSDS MSG value.

References CCSDS_PKT_MSG, CCSDS_pktChksumCalc(), and NULL.